[PATCH] net: thunderx: Fix unintentional sign extension issue

[PATCH] net: thunderx: Fix unintentional sign extension issue

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The shifting of the u8 integers rq->caching by 26 bits to
the left will be promoted to a 32 bit signed int and then
sign-extended to a u64. In the event that rq->caching is
greater than 0x1f then all then all the upper 32 bits of
the u64 end up as also being set because of the int
sign-extension. Fix this by casting the u8 values to a
u64 before the 26 bit left shift.

Addresses-Coverity: ("Unintended sign extension")
Fixes: 4863dea3fab0 ("net: Adding support for Cavium ThunderX network controller")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/ethernet/cavium/thunder/nicvf_queues.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
index f782e6af45e9..50bbe79fb93d 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
@@ -776,7 +776,7 @@ static void nicvf_rcv_queue_config(struct nicvf *nic, struct queue_set *qs,
 	mbx.rq.msg = NIC_MBOX_MSG_RQ_CFG;
 	mbx.rq.qs_num = qs->vnic_id;
 	mbx.rq.rq_num = qidx;
-	mbx.rq.cfg = (rq->caching << 26) | (rq->cq_qs << 19) |
+	mbx.rq.cfg = ((u64)rq->caching << 26) | (rq->cq_qs << 19) |
 			  (rq->cq_idx << 16) | (rq->cont_rbdr_qs << 9) |
 			  (rq->cont_qs_rbdr_idx << 8) |
 			  (rq->start_rbdr_qs << 1) | (rq->start_qs_rbdr_idx);
-- 
2.30.2

Re: [PATCH] net: thunderx: Fix unintentional sign extension issue

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Fri,  9 Apr 2021 14:07:26 +0100 you wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The shifting of the u8 integers rq->caching by 26 bits to
> the left will be promoted to a 32 bit signed int and then
> sign-extended to a u64. In the event that rq->caching is
> greater than 0x1f then all then all the upper 32 bits of
> the u64 end up as also being set because of the int
> sign-extension. Fix this by casting the u8 values to a
> u64 before the 26 bit left shift.
> 
> [...]

Here is the summary with links:
  - net: thunderx: Fix unintentional sign extension issue
    https://git.kernel.org/netdev/net-next/c/e701a2584036

You are awesome, thank you!
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